Halogenated ketones as herbicide antidotes

ABSTRACT

Herbicidal compositions comprising an active herbicidal compound and antidote therefor and the methods of use; the antidote compounds correspond to halogenated ketones having the formula ##EQU1## wherein R 1  is halocycloalkyl, lower alkyl, lower haloalkyl, phenyl, benzyl and p-tolyl, and R 2  is lower haloalkyl, α-halobenzyl, haloacetonyl and haloalkylenecarboalkoxy, provided that when R 2  is difluoromonochloromethyl, R 1  is other than monofluorodichloromethyl.

This is a continuation, of application Ser. No. 307,301, filed Nov. 16,1972 now abandoned.

BACKGROUND OF THE INVENTION

Among the many herbicidal compounds commercially available, thethiocarbamates alone or admixed with other herbicides, such as thetriazines, have reached a relatively high degree of commercial success.These herbicides are immediately toxic to a large number of weed pestsat different concentrations varying with the resistance of the weedpests. Some examples of these compounds are described and claimed in theU.S. Pat. No. 2,913,327, 3,037,853, 3,175,897, 3,185,721, 3,198,786 and3,582,314.

It has been found in practice that the use of these thiocarbamates asherbicides on crops sometimes causes serious injuries to the crop plant.When used in the recommended amounts in the soil to control manybroadleaf weeds and grasses, serious malformation and stunting of thecrop plants result. This abnormal growth in the crop plants results inloss of crop yield. Previous attempts to overcome this problem involvesthe treatment of the crop seed with certain antagonistic agents prior toplanting, see U.S. Pat. No. 3,131,509 and 3,564,768. These antagonisticagents have not been notably successful. The aforementioned patentspecifically exemplifies the treatment of seeds employing compounds of adifferent chemical class not suggestive of the present invention.

DESCRIPTION OF THE INVENTION

It has been discovered that plants can be protected against injury byvarious herbicides, for example, the thiocarbamate-type herbicides,alone or mixed with other herbicidal compounds and/or the tolerance ofthe plants can be substantially increased to the active compounds of theabove-noted U.S. Patents by adding to the soil an antidote compoundcorresponding to the following formula ##STR1## wherein R₁ ishalocycloalkyl, lower alkyl, lower haloalkyl, phenyl, benzyl and p-tolyland R₂ is lower haloalkyl, α-halobenzyl, haloacetonyl andhaloalkylenecarboalkoxy, provided that when R₂ isdifluoromonochloromethyl, R₁ is other than monofluorodichloromethyl.

In the description of the halogenated ketones as compounds useful in theherbicidal antidote method of this invention, the following embodimentsare intended for the various groups: The term halo preferably refers tofluoro, chloro and bromo substitution in mono, di, tri, tetra and persubstitution. Halo also is intended to relate to mixed halogensubstitution, such as in dichloromonofluoromethyl, and the like.Cycloalkyl preferably includes those members containing from 3 to 6carbon atoms, inclusive, such as cyclopropyl, cyclobutyl, cyclopentyland cyclohexyl. The term lower alkyl preferably includes those memberscontaining from 1 to 4 carbon atoms, inclusive, in both branched andstraight chain configuration; the term halo can be used as a prefix withthese groups as defined herein, for example, dichloromethyl,chlorodifluoromethyl, trichloromethyl, 1,-bromopropyl and the like. Theterm haloalkylenecarboalkoxy preferably includes those members having atotal of 3 to 8 carbon atoms, inclusive.

As an alternative mode of action, the compounds of this invention mayinterfere with the normal herbicidal action of the thiocarbamate-typeand other herbicides to render them selective in their action. Whichevermode of action is present, the corresponding beneficial and desirableeffect is the continued herbicidal effect of the thiocarbamate or otherherbicide with the accompanying decreased herbicidal effect on desiredcrop species. This advantage and utility will become more apparenthereinafter.

Therefore, the terms herbicide, antidote or antidotal amount, is meantto describe that effect which tends to counteract the normal injuriousherbicidal response that the herbicide might otherwise produce. Whetherit is to be termed a remedy, interferant, protectant, or the like, willdepend upon the exact mode of action. The mode of action is varied, butthe effect, which is desirable, is the result of the method of treatingthe soil in which a crop is planted. Hitherto, there have been nosystems which have been satisfactory for this purpose.

The compounds of this invention represented by the above formula, can beprepared by several different procedures depending upon the startingmaterials and desired products.

Many of the compounds of the instant method are known in the prior art.If the compound was not available from a commercial source, it wasprepared by normal halogenation processes. For example, some compoundswere brominated or chlorinated by mixing bromine or chlorine with theunhalogenated starting material. An inert solvent such as methylenechloride was used to facilitate the reaction and the work-up procedure.For more vigorous halogenation conditions it was necessary to employ acatalyst such as aluminum trichloride. In all reactions, normal work-upprocedures were used to recover the final product.

The following examples are illustrative of the preparation of some ofthe compounds of the instant invention.

EXAMPLE I

Preparation of 3-Bromo-2,4-pentanedione.

Pentanedione (50 g., 0.5 mole) was dissolved in 100 ml. methylenechloride with 0.2 g. aluminum trichloride present. Bromine (80 g., 0.5mole) was added to the solution while stirring. After the addition wascomplete, stirring was continued for about 1 hour. The solvent wasremoved in vacuo. There was obtained 69.5 g. of the title compound, adark red oil.

EXAMPLE II

Preparation of α,α-dichloroethylbenzoylacetate.

Ethylbenzoylacetate, 104 g. (0.54 mole), was treated with chlorine gasin 300 ml. carbon tetrachloride as the solvent. The absorption of thechlorine gas is a spontaneous and mildly exothermic reaction. A waterbath was used to keep the temperature between 30°-35°C. When the secondequivalent of chlorine is to be added, the reaction decreased. A warmwater bath was needed to aid the addition reaction to continue tocompletion. The solvent was removed in vacuo. After fractionaldistillation at 3mm/Hg., there was obtained as the main fraction 121 g.of the title compound, b.p. 137°C./3mm/Hg., n_(D) ²⁵ = 1.5286.

The following is a table of compounds which are within the scope of thepresent invention. Compound numbers have been assigned to them and areused for identification throughout the balance of the specification.

                                      TABLE I                                     __________________________________________________________________________     ##STR2##                                                                                              m.p. °C.,                                     COMPOUND                 b.p. °C.,                                     NUMBER R.sub.1   R.sub.2 or n.sub.D.sup.30                                    __________________________________________________________________________    1      4-Cl-cyclohexyl                                                                         CH.sub.2 Cl                                                                           101-102°C. m.p.                               2      phenyl    CHBr.sub.2                                                                            33-35°C. m.p.                                 3      methyl    CHCl.sub.2                                                                            1.4365                                               4      phenyl    CBr.sub.2 CH.sub.3                                                                    1.5765                                               5      CCl.sub.3 CHCl.sub.2                                                                            192°C. b.p.                                   6      phenyl    CH.sub.2 Br                                                                           49°C. m.p.                                    7      p-CH.sub.3 -phenyl                                                                      CH.sub.2 Br                                                                           52°C. m.p.                                    8      Cl.sub.2 CH                                                                             CHCl.sub.2                                                                            1.4946                                               9      CF.sub.2 Cl                                                                             CF.sub.2 Cl                                                                           colorless liquid                                     10     CH.sub.3                                                                                 ##STR3##                                                                             dark red oil                                         11     phenyl-CH.sub.2                                                                         phenyl-CHBr                                                                           yellow liquid                                        12     phenyl                                                                                   ##STR4##                                                                             1.5286                                               13     phenyl    CHBrCH.sub.2 CH.sub.3                                                                 yellow oil                                           14     CH.sub.3  CHBrCH.sub.3                                                                          yellow liquid                                        __________________________________________________________________________

The compounds of this invention were employed in effective herbicidalantidote compositions comprising thiocarbamates and triazines incombination with antidote compounds described hereinabove. They weretested in the following manner.

Corn Seed Treatment Test

Small flats were filled with Felton loamy sand soil. Soil incorporatedherbicides were applied at this time. The soil from each flat was placedinto a five-gallon cement mixer where the soil was mixed as theherbicides were applied using a predetermined amount of a stock solutioncontaining 936 mg. of 75.5% active ingredient to 100 ml. of water. Oneml. of stock solution was applied to the soil in a volumetric pipet foreach pound of herbicide desired. One ml. of stock solution contained 7mg. of herbicide which equals one pound per acre when applied to thesoil in the flats. After the herbicide incorporation, the soil wasplaced back into the flats.

Flats of herbicide-treated and untreated soil were then ready to beplanted. A pint sample of soil was removed from each flat and placednext to each flat for later use in covering up the seeds. The soil wasleveled and rows one-half inch deep were made for planting seeds.Alternating rows of treated and untreated crop seeds were sown. In eachtest, six PAG 344T or DeKalb XL 374 field corn seeds were planted ineach row. Rows were approximately 11/2 inches apart in the flat. Seedswere treated by placing 50 mg. of the antidote compound with 10 grams ofcorn seed (0.5% w/w) in a suitable container and shaking them until theseeds were uniformly covered with the compound. Antidote compounds werealso applied as liquid slurries and powders or dusts. In some cases,acetone was used to dissolve powdered or solid compounds so they couldbe more effectively applied to the seeds.

After the flats were seeded, they were covered with the one pint of soilwhich had been removed just prior to planting. Flats were placed ongreenhouse benches where temperatures ranged from 70°-90°F. Flats werewatered by sprinkling as needed to assure good plant growth. Percentcontrol ratings were taken two, three and four weeks after thetreatments were applied.

In each test, the herbicide was applied alone, in combination with theseed protectant, and the seed protectant was applied alone to check forphytotoxicity. The untreated adjacent row was employed to observe anybeneficial lateral movement of the antidote compound through the soil.The degree of the effect was noted by comparison with the control. Theresults of these tests are tabulated in Table II.

                  TABLE II                                                        ______________________________________                                        Per Cent Injury to Corn from EPTC*                                            Seed Treatment Test                                                                        Per Cent Injury, 2 weeks                                                        Treatment  Untreated                                           COMPOUND       Seed       Seed                                                NUMBER         (0.5% w/w) Adjacent Row                                        ______________________________________                                        1              40         97                                                  2              20         98                                                  3              20         35                                                  4               0         73                                                  5              20         80                                                  6              60         75                                                  7              60         80                                                   8**           30         60                                                  EPTC 6E Untreated Seed                                                                       --         70                                                                            80      (4 weeks)                                   ______________________________________                                          *=S-ethyl dipropylthiocarbamate 6E: 6 lb/A pre-plant incorporat              **=Seed treatment 0.05% w/w                                              

Procedure: Multicrop Antidote Screen

Plastic flats were filled with Felton loamy sand soil. Since a varietyof grass and broadleaf crops were used in these tests, EPTAM (EPTC) wasincorporated at 1/2 and 5 lb/A, while a constant rate of 5 lb/A of theadditive was used. EPTAM (EPTC) and the herbicide additive were appliedseparately by pipetting measured amounts of the apprpriate stocksolutions into the soil during incorporation in a 5 gallon rotary cementmixer. Stock solutions for EPTAM were prepared as follows:

A. 1/2 lb/A: 670 mg. of EPTC 6E (75.5% a.i.) was diluted with 500 ml. ofdeionized water so that 2 ml. equals 1/2 lb/A/plastic flat.

B. 5 lb/A: 6700 mg. of EPTC 6E (75.5%) was diluted with 500 ml. ofdeionized water so that 2 ml. equals 5 lb/A/plastic flat.

Additive stock solutions were prepared by diluting 102 mg. of technicalmaterial with 10 ml. of acetone 1% Tween 20 (polyoxyethylene sorbitanmonolaurate) so that 2 ml. equals 5 lb/A/flat.

After the soil was treated with both herbicide and additive the soil wastransferred from the mixer back into the flat where it was then preparedfor seeding. The initial step in preparation was to remove a one pintsample of soil from each flat to be retained and used to cover the seedsafter planting. The soil was then leveled and rows one-quarter inch deepwere made in each flat. Flats treated with 5 lb/A of EPTAM were seededto DeKalb XL-44 corn (Zea maize), US H9 sugarbeets (Beta vulgare), smallseeded gray striped sunflower (Helianthus annus), Acala cotton(Gossypium hirsutum), Brag soybeans (Glycine max) and oilseed rape(Brassica napus). Flats treated with 1/2 lb/A of EPTAM were seeded tored oats (Avena byzantina), R-10 milo (Sorgum vulgare), Fremont HRSwheat (Triticum aestivum), giant foxtail (Seteria feberii), Calrose rice(Oryza sativa) and Blue Mariate barley (Hordeum vulgare). Seeds werethen covered with the pint soil sample removed prior to seeding.

The flats were then placed on greenhouse benches where temperatures weremaintained between 70°-90°F. The soil was watered by sprinkling toassure good plant growth.

Injury ratings were taken 2 and 4 weeks after the treatments wereapplied. Soil treated with EPTAM alone at 1/2 or 5 lb/A was included toprovide a basis for determining the amount of injury reduction providedby the herbicide antidotes. The per cent protection of variousrepresentative crops is reported in Table III. The per cent protectionis determined by a comparison with flats not treated with the candidateantidote.

                                      TABLE III                                   __________________________________________________________________________    Multicrop Screen Results                                                      Per Cent Protection                                                           COMPOUND     Rate of       % Protection                                       NUMBER Herbicide                                                                           Herbicide lb/A                                                                         Crop (2 weeks)                                          __________________________________________________________________________     2*    EPTC  0.5      sorghum                                                                            85  (4 weeks)                                                   3.0      corn 100                                                 9     EPTC  3.0      corn 100                                                             3.0      soybeans                                                                           80  (4 weeks)                                      10     EPTC  3.0      corn 100                                                             3.0      soybeans                                                                           60  (4 weeks)                                      11     EPTC  3.0      corn 50                                                 12     EPTC  3.0      corn 100                                                 2     Atrazine**                                                                          2.0      cotton                                                                             40  (3 weeks)                                       9     Atrazine                                                                            2.0      cotton                                                                             50  (3 weeks)                                      13     EPTC  0.5      sorghum                                                                            67  (4 weeks)                                      14     EPTC  0.5      rice 86  (4 weeks)                                                   5.0      soybeans                                                                           47  (4 weeks)                                                   5.0      corn 52  (4 weeks)                                      __________________________________________________________________________     *=Antidote used at 10 lb/A                                                    **=2-chloro-4-ethylamino-6-isopropylamino-s-triazine                     

The antidote compounds and compositions of the present invention can beused in any convenient form. Thus, the antidote compounds can beformulated into emulsifiable liquids, emulsifiable concentrates, liquid,wettable powder, powders, granular or any other convenient form. In itspreferred form, a non-phytotoxic quantity of an herbicidal antidotecompound is admixed with a selected herbicide and incorporated into thesoil prior to or after planting the seed. It is to be understood,however, that the herbicides can be incorporated into the soil andthereafter the antidote compound can be incorporated into the soil.Moreover, the crop seed itself can be treated with a non-phytotoxicquantity of the compound and planted into the soil which has beentreated with herbicides, or untreated with the herbicide andsubsequently treated with the herbicide. The addition of the antidotecompound does not affect the herbicidal activity of the herbicides.

The amount of antidote compound present can range between about 0.001 toabout 15 parts by weight of antidote compound described herein per eachpart by weight of herbicide. The exact amount of antidote compound willusually be determined on economic ratios for the most effective amountusable. It is understood that a non-phytotoxic quantity of antidotecompound will be employed in the herbicidal compositions describedherein.

The herbicides indicated in the tables and elsewhere are used at rateswhich produce effective control of undesirable vegetation. The range ofrates employed herein produce representative results within therecommended amounts set forth by the supplier. Therefore, the weedcontrol in each instance is commercially acceptable within the desiredor recommended amount.

It is clear that the classes of herbicidal agents described andillustrated herein are characterized as effective herbicides exhibitingsuch activity. The degree of this herbicidal activity varies amongspecific compounds and among combinations of specific compounds withinthe classes. Similarly, the degree of activity to some extent variesamong the species of plants to which a specific herbicidal compound orcombination may be applied. Thus, selection of a specific herbicidalcompound or combination to control undesirable plant species readily maybe made. Within the present invention are prevention of injury to adesired crop species in the presence of a specific compound orcombination may be achieved. The beneficial plant species which can beprotected by this method is not intended to be limited by the specificcrops employed in the examples.

The herbicidal compounds employed in the utility of this invention areactive herbicides of a general type. That is, the members of the classesare herbicidally effective against a wide range of plant species withsome degree of discrimination between desirable and undesirable species.The method of controlling vegetation comprises applying an herbicidallyeffective amount of the hereindescribed herbicidal compounds to the areaor plant locus where control is desired. The compositions as set forthin this invention include those wherein the preferred active herbicidalcompound is selected from S-ethyl dipropylthiocarbamate; S-ethyldiisobutyl thiocarbamate, S-propyl dipropyl thiocarbamate,S-2,3,3-trichloroallyl-diisopropyl thiocarbamate, S-ethyl cyclohexylethyl thiocarbamate,2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide, S-ethylhexahydro-1H-azepine-1-carbothioate, 2-chloro-N-isopropylacetanilide,N,N-diallyl-2-chloroacetamide, S-4-chlorobenzyl diethyl thiocarbamate,2-chloro-4-ethylamino-6-isopropylamino-s-triazine,2-chloro-4,6-bis(ethylamino)-s-triazine,2(4-chloro-6-ethylamine-s-triazine-2-ylamino)-2-methylpropionitrile,2-chloro-4-cyclopropylamino-6-isopropylamino-s-triazine,2,4-dichlorophenoxyacetic acid, its esters and salts, and3-(3,4-dichlorophenyl)-1,1-dimethylurea and combinations thereof.

An herbicide as used herein means a compound which controls or modifiesthe growth of vegetation or plants. Such controlling or modifyingeffects include all deviations from natural development; for example,killing, retardation, defoliation, desiccation, regulation, stunting,tillering, stimulation, dwarfing and the like. By "plants" it is meantgerminant seeds, emerging seedlings, and established vegetation,including the roots and above-ground portions.

What is claimed is:
 1. The method of reducing injury to corn plantsinjured by thiocarbamate herbicides comprising applying to the cornseeds prior to planting a non-phytotoxic antidotally effective amount ofa compound corresponding to the formula ##EQU2## wherein R₁ ishalocycloalkyl in which halo is fluoro, chloro or bromo and containingfrom 3 to 6 carbon atoms, inclusive, lower alkyl containing from 1 to 4carbon atoms, inclusive, lower haloalkyl in which halo is fluoro, chloroor bromo and containing from 1 to 4 carbon atoms, inclusive, phenyl,benzyl, and p-tolyl; R₂ is lower haloalkyl in which halo is fluoro,chloro or bromo and containing from 1 to 4 carbon atoms, inclusive,α-halobenzyl in which halo is fluoro, chloro or bromo, haloacetonyl inwhich halo is fluoro, chloro or bromo, and haloalkylenecarboalkoxy inwhich halo is fluoro, chloro or bromo and having a total of 3 to 8carbon atoms, inclusive, provided that when R₂ isdifluoromonochloromethyl, R₁ is other than monofluorodichloromethyl. 2.The method according to claim 1 in which R₁ is lower alkyl and R₂ ishaloalkyl.
 3. A method according to claim 2 in which R₁ is methyl and R₂is dichloromethyl.
 4. A method according to claim 2 in which R₁ ismethyl and R₂ is 1-bromoethyl.
 5. The method according to claim 1 inwhich R₁ is phenyl and R₂ is haloalkyl.
 6. A method according to claim 5in which R₂ is dibromomethyl.
 7. A method according to claim 5 in whichR₂ is 1,1-dibromoethyl.
 8. A method according to claim 5 in which R₂ isbromomethyl.
 9. A method according to claim 5 in which R₂ is1-bromopropyl.
 10. A method according to claim 1 in which R₁ is4-chlorocyclohexyl and R₂ is chloromethyl.
 11. The method according toclaim 1 in which R₁ is lower haloalkyl and R₂ is lower haloalkyl.
 12. Amethod according to claim 11 in which R₁ is trichloromethyl and R₂ isdichloromethyl.
 13. A method according to claim 11 in which R₁ isdichloromethyl and R₂ is dichloromethyl.
 14. A method according to claim11 in which R₁ is chlorodifluoromethyl and R₂ is chlorodifluoromethyl.15. A method according to claim 1 in which R₁ is phenyl and R₂ isdichloromethylenecarboethoxy.
 16. A method according to claim 1 in whichR₁ is lower alkyl and R₂ is haloacetonyl.
 17. A method according toclaim 16 in which R₁ is methyl and R₂ is 1-bromoacetonyl.
 18. A methodaccording to claim 1 in which R₁ is benzyl and R₂ is α-bromobenzyl. 19.A method according to claim 1 in which R₁ is p-tolyl and R₂ is lowerhaloalkyl.
 20. A method according to claim 19 in which R₂ isbromomethyl.
 21. The method of reducing injury to crops selected fromcorn, sorghum, soybeans, cotton and rice injured by thiocarbamateherbicides comprising applying to the soil in which said crops are togrow and in which said herbicides are to be applied a non-phytotoxicantidotally effective amount of a compound corresponding to the formula##STR5## wherein R₁ is halocycloalkyl in which halo is fluoro, chloro orbromo and containing from 3 to 6 carbon atoms, inclusive, lower alkylcontaining from 1 to 4 carbon atoms, inclusive, lower haloalkyl in whichhalo is fluoro, chloro or bromo and containing from 1 to 4 carbon atoms,inclusive, phenyl, benzyl, and p-tolyl; R₂ is lower haloalkyl in whichhalo is fluoro, chloro or bromo and containing from 1 to 4 carbon atoms,inclusive, α-halobenzyl in which halo is fluoro, chloro or bromo,haloacetonyl in which halo is fluoro, chloro or bromo, andhaloalkylenecarboalkoxy in which halo is fluoro, chloro or bromo andhaving a total of 3 to 8 carbon atoms, inclusive, provided that when R₂is difluoromonochloromethyl, R₁ is other than monofluorodichloromethyl.22. The method according to claim 21 in which R₁ is lower alkyl and R₂is haloalkyl.
 23. The method according to claim 22 in which R₁ is methyland R₂ is dichloromethyl.
 24. The method according to claim 22 in whichR₁ is methyl and R₂ is 1-bromoethyl.
 25. The method according to claim21 in which R₁ is phenyl and R₂ is haloalkyl.
 26. The method accordingto claim 25 in which R₂ is dibromomethyl.
 27. The method according toclaim 25 in which R₂ is 1,1-dibromoethyl.
 28. The method according toclaim 25 in which R₁ is bromomethyl.
 29. The method according to claim25 in which R₂ is 1-bromopropyl.
 30. The method according to claim 21 inwhich R₁ is 4-chlorocyclohexyl and R₂ is chloromethyl.
 31. The methodaccording to claim 21 in which R₁ is lower haloalkyl and R₂ is lowerhaloalkyl.
 32. The method according to claim 31 in which R₁ istrichloromethyl and R₂ is dichloromethyl.
 33. The method according toclaim 31 in which R₁ is dichloromethyl and R₂ is dichloromethyl.
 34. Themethod according to claim 31 in which R₁ is chlorodifluoromethyl and R₂is chlorodifluoromethyl.
 35. The method according to claim 21 in whichR₁ is phenyl and R₂ is dichloromethylenecarboethoxy.
 36. The methodaccording to claim 21 in which R₁ is lower alkyl and R₂ is haloacetonyl.37. The method according to claim 36 in which R₁ is methyl and R₂ is1-bromoacetonyl.
 38. The method according to claim 21 in which R₁ isbenzyl and R₂ is α-bromobenzyl.
 39. The method according to claim 21 inwhich R₁ is p-tolyl and R₂ is lower haloalkyl.
 40. The method accordingto claim 39 in which R₂ is bromomethyl.